Contradiction with 1 Kings 8:22
Solomon stands while praying, whereas Paul kneels in Acts 20:36.
1 Kings 8:22: And Solomon stood before the altar of the LORD in the presence of all the congregation of Israel, and spread forth his hands toward heaven:
Contradiction with Matthew 6:5
Jesus warns against praying for outward appearance, while Acts 20:36 describes a public prayer.
Matthew 6:5: And when thou prayest, thou shalt not be as the hypocrites [are]: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward.
Contradiction with Matthew 26:39
Jesus fell on His face to pray, differing from the kneeling posture in Acts 20:36.
Matthew 26:39: And he cometh unto the disciples, and findeth them asleep, and saith unto Peter, What, could ye not watch with me one hour?
Contradiction with Mark 11:25
Instructs to stand while praying, in contrast to kneeling in Acts 20:36.
Mark 11:25: And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses.